This Proposal is designed to address: 1) an important disease that needs novel drugs - no new drugs for Mycobacterium tuberculosis in 40 years and multi-drug resistant strains as well as extreme drug resistant strains are becoming more common;2) the lack of structural information for an entire class of drug targets, the membrane proteins - less than 1% of known protein structures are membrane proteins, while 25 to 30% of the genome of most organisms code for membrane proteins - in addition, membrane proteins are more frequently effective drug targets than water-soluble proteins;3) biological, functional and structural characterization of validated targets - we will characterize only those proteins that are essential for Mtb growth and by targeting membrane proteins, especially the outer membrane proteins, access to the drug targets will not require transport across the bacterial membranes. 4) a gap in screening technology - new small molecule screening technologies based on solution and solid state NMR spectroscopy will be developed specifically for membrane proteins. We have developed an Initial Target List from preliminary results and from literature on essential genes, virulence factors, identification of outer membrane proteins and numerous individual studies on specific potential targets. Some of these proteins are already validated as high potential pharmaceutical targets, these form a Prioritized Target List that will allow all of the Projects and Cores to initiate their efforts on the first day of funding. From biological function (Project 1) to assay development (Project 2) to structural characterization (Project 3) these activities will work closely together. Assays coupled with molecular structure will help establish structure-activity-relationships. Assay development will enable screening against small molecules important for understanding function and potentially important for structural studies. The assays we develop and the ligands we identify will fuel biological experiments designed to understand the life and infection cycle of Mtb. These ligands will be useful as lead compounds in drug discovery, and while this is beyond the scope of this Program, this team will protect the intellectual property for those who may want to pursue the development of drugs for these membrane protein targets. To accomplish these goals a unique team of investigators has been brought together with extensive knowledge of: Mycobacterium tuberculosis, essential Mtb genes, membrane protein physiology, molecular biology, biophysics, and structural characterization. The Program offers access to two of the premier NMR facilities in the world along with their expertise in methodology and technology development, in addition, the Team brings with it unique expression libraries of Mtb membrane proteins and the superb screening facilities and expertise of the Burnham Institute.